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ISARIC identifies four COVID-19 risk groups

Doctors treating hospitalised patients

People admitted to hospital with COVID-19 can be divided into four distinct groups, according to data from the world’s largest study of patients with the disease.

Researchers used clinical information and tests carried out on arrival at hospital to predict the patients’ risk of death – ranging from low to very high.

The COVID-19 risk identification tool will help clinical staff choose the best course of treatment for patients admitted to hospital.

It was built by the ISARIC Coronavirus Clinical Characterisation Consortium, involving researchers from the universities of Edinburgh, Glasgow and Liverpool, and Imperial College London.

The project was funded by UKRI and by the Department of Health and Social Care through the National Institute for Health Research, as part of the UK government’s COVID-19 rapid research response.

Predicting risk

The ISARIC researchers used data from 35,000 patients admitted to hospital between February and May 2020 who met the criteria for one of the four groups.

The tool was tested and its accuracy confirmed using data from a further 22,000 patients hospitalised from the end of May to the end of June 2020.

Some of the data used to identify which group a person falls into – and therefore their risk of dying – included age, sex, the number of pre-existing conditions, respiratory rate on admission and the results of two blood tests.

One in every 100 patients in the low-risk group was found to be at risk of dying.

That number was 10 in 100 patients in the intermediate-risk group, 31 in 100 in the high-risk group and 62 in 100 in the very high-risk group.

The first accurate risk tool for COVID-19

The categorisations make new treatment pathways possible, the researchers say.

People who fall into low-risk subgroups could be treated at home, while those in the high or very high-risk groups could have more aggressive treatment like early admission to critical care.

This is the first accurate risk tool for COVID-19 patients. Existing tools for pneumonia or sepsis do not offer accurate predictions due to the differences between diseases.

One limitation of this new tool is that it can only be used on hospital patients, and not within the community.

Pandemic preparedness

Professor Fiona Watt, Executive Chair of the Medical Research Council said:

These results highlight the benefits of being prepared in advance of the emergence of new pandemics such as COVID-19.

The work is the latest result from ISARIC – a global network of clinicians and scientists who have been preparing to prevent disease and death from severe outbreaks since 2012 in readiness for a pandemic such as this.

It involved 260 hospitals across England, Wales and Scotland.

The ISARIC 4C study includes two thirds of all people admitted to hospital with COVID-19.

See the published findings in the British Medical Journal (BMJ).

Last updated: 28 October 2020

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